/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: Admin
 * Date: 2022-05-10
 * Time: 20:59
 */
public class MyLinkedList {


    static class ListNode {
        public ListNode next;
        public ListNode perv;
        public int val;

        public ListNode(int val) {
            this.val = val;
        }
    }

    public ListNode head;
    public ListNode last;

    //头插法
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if(this.head == null) {
            head = node;
            last = node;
        } else {
            node.next = head;
            head.perv = node;
            head = node;
        }

    }

    //尾插法
    public void addLast(int data) {
        ListNode node = new ListNode(data);

        if(this.head == null) {
            head = node;
            last = node;
        } else {
            last.next = node;
            node.perv = last;
            last = node;
        }
    }

    private ListNode addIndexOf(int index) {
        ListNode cur = head;
        while(index > 0) {
            cur = cur.next;
            index--;
        }
        return cur;
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data) {
        if(!(index >= 0 && index <=size())) {
            return;
        }

        if(index == 0) {
            addFirst(data);
            return;
        }

        if(index == size()) {
            addLast(data);
            return;
        }

      ListNode cur =  addIndexOf(index);
      ListNode node = new ListNode(data);
        node.next = cur;
        cur.perv.next = node;
        node.perv = cur.perv;
        cur.perv = node;
    }

    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key) {
        ListNode cur = head;

        while(cur != null ) {
            if(cur.val == key) {
                return true;
            }
            cur =cur.next;
        }
        return false;
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key) {
        ListNode cur =head;
        while(cur != null ) {
            if(cur.val == key) {
                if(cur == head) {
                    head = head.next;
                    if(head != null) {
                        head.perv = null;
                    }
                } else {
                    if(cur.next == null ) {
                        last = last.perv;
                        last.next = null;
                    } else {
                        cur.perv.next = cur.next;
                        cur.next.perv = cur.perv;
                    }
                }
                return;
            }
            cur = cur.next;
        }
    }

    //删除所有值为key的节点
    public void removeAllKey(int key) {
        ListNode cur =head;
        while(cur != null ) {
            if(cur.val == key) {
                if(cur == head) {
                    head = head.next;
                    if(head != null) {
                        head.perv = null;
                    }
                } else {
                    if(cur.next == null ) {
                        last = last.perv;
                        last.next = null;
                    } else {
                        cur.perv.next = cur.next;
                        cur.next.perv = cur.perv;
                    }
                }
            }
            cur = cur.next;
        }
    }

    //得到单链表的长度
    public int size() {
        ListNode cur = head;
        int count = 0;

        while(cur != null ) {
            count++;
            cur = cur.next;
        }
        return count;
    }

    public void display() {
        ListNode cur = head;

        while(cur != null) {
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    public void clear() {
        ListNode cur = head;
        while(cur != null) {
            ListNode curNext = cur.next;
            cur.perv = null;
            cur.next = null;
            cur = curNext;
        }
        head = null;
        last = null;
    }

}
